Method of making fiber-rubber material



H Patented Feb. 2, 1932 expensive,

man sTATEsPATENT OFFICE REED r. ROSE AND ALLEN r. owEN, or JAoxsoNHEIGHTS, EW YoiiK, ssIeNons 'ro THE MECHANICAL RUBBER COMPANY, orCLEVELAND, 01110, A CORPORATION on NE JERSEY METHOD or MAKINGFIBER-RUBBER MATERIAL No Drawing.

' more particularly to a leather substitute suitable for uses similar tothose in which sole leather is employed.

Leather of the sole leather type has a wide use inrthe arts, moreparticularly for shoe parts such assoles'and doublers, counters and toeboxes, belting, gaskets, pump valves and cups, shims such as body shimsfor. automobiles and many other purposes. However, leather of thischaracteris relatively since for the highest class articles onlyselected parts of the best grade hides can be used; Moreover, while soleleather has many desirable qualities which fit it for the above andother purposes, it is open to a x number of objections the mostimportant of which is lack of uniformity which is apparent not onlybetween different lots butto a great extent even in the individualhides. itstensile strength and resistance to flexing and abrasion arerelatively good, there. is Y room for considerable improvement in theserespects, and it is also open to the objection that it iswater-absorbent, and when water soaked, it loses its resistancetoabrasion and cutting. and loses in tensile strength,and it has thefurther disadvantage that after drying,,itbecomes unduly stiff and doesnot recover its original physical characteristics. Furthermore, itdeteriorates in the presence of strong alkaliesand acids, and hencecannot be used for purposes where resistance to these is required. Anobject of our inventlon is to provide-a uniformly dense, tough,.hightensile, flexible,

water and abrasion resistant composition. of

fiber and rubber. Another object is to provide a sole leather substitutewhich can be used for every purpose for which sole leather is now usedhaving properties substantially equalling or surpassingthose of' geninueleather. Another object is to provide a finished shoe bottoming blankdirectly from an aqueous'suspension offiber and rubber. further objectis to provide shoe soles, dou blers, counters, toe boxes and otherfindings of improved quality and to provide an inexpensive method ofmanufacturing the Application filed August 11,

, While 1927. Serial No.. 212,356.

same. A still further object is to provide a method of preparing andtreating the composition by which the desired qualities are obtained.Further objects will appear fromalone or compounded, the material being.

characterized by its density, toughness, high tensile and high flexingtest, and resistance to water and'abrasion. The invention furthercomprises the method for making the material.

In carrying out the invention, an aqueous suspension of fiber mixed withan aqueous dispersion of rubber is first prepared. While it is preferredto use vegetable fibers such as cotton any other fiber or mixturesthereof possessing the desired characteristics may be used. The cottonor other fiber is first partly hydrolized in any"'suita-ble mannerpreferably by treating with water in any suitable type of a heatingengine or hollander. The beating operation is carried outwith care sothat the fibers are drawn or brushed out and not cut fine andiscontinued until the fiber has been hydrolized to such an extent that thefiber surfaces have been reduced to a gelatinous condition. Any suitableaqueous dispersion of rubber, latex, unvulcanized or vulcanized, or anartificial dispersion of rubber,- is then added to The invention alsoincludes the addiif" desired, of any suitable compoundfillingingredients including protecas glue, treated starches,

tion, mg or tive colloids such casein, etc. and

which-it is desired to. modify the properties.

After the batch .is thoroughly mixed, the

such as natural I any other ingredients by the above prepared aqueoussuspension of fiber.

coagulation. It is preferred-to utilize the two-sta e method ofdepositing the rubber ished article in any of the following ways:.

The solid material of the batch may be deposited in sheet form of thedesired thickness directly from the suspension in water by the use of apaper machine of theFourdrinie'r or cylinder type. After the formationof a sheet of suitablethickness, the wet sheet is then cold pressedpreferably between the plates or platens .of a press at a pressure notto exceed that at which the sheet will flow or spread while in its wetcondition. The main purpose of this pressing is toremove moisture and toinitially consolidate or compact the material. The pressure used can bebetween the limits of 50 to 500 lbs, but for the higher pressures it ispreferable to apply it gradually in order not to distort the position ofthe fibers inthe sheet and spread the same. If products of a mediumquality are desired such as shoe doublers or mid-soles, counters,

I toe boxes and automobile body shims the moisture content may bereduced to form 10-15% in one drying operation. However, if a betterquality product is desired the drying step should be carried to a pointwhere the material contains between 20 and 30% moisture and should befollowed by an intermediate pressing step; using a pressure of from 500to 1200 lbs. per square inch with a cold press. After this intermediatepressing step the dryin is continued until amoisture content of rom10-15% is reached. After the cold pressing the sheet is dried inany-suitable manner until its moisture contenthas been further reduced.Fol: lowing the drying step, the sheet is then hot pressed at atemperature and under a pressure which will vary somewhat withconditions and the urpose for which the finished material is to e used.

That is, if a relatively high heat and long pressing are employed, thepressure may be somewhat reduced, while if the heat is lower and thepressing of comparatively short duration, the pressure should begreater. Other things being equal, the higher the pressure the greaterthe density, toughness, tensile strength, .water and abrasionresistancev of the sheet, but if the pressure is unduly high, theflexibility maybe decreased to such an extent that the material is nblonger suitable for shoe bottoming purposes requiring considerableflexibility but may .be-used for other purposes where flexibility is notan essential factor. The pressure should not be substantially below 800lbs. in the making of a sole or doubler material, and by reason of theaforesaid decrease in flexibility, it should not substantially exceed2000 lbs, the pr eferred limits for the pressing being from about 1200to 2000 lbs. at a temperature of from 225 F. to 310 Fffor theseproducts.

While, if desired, vulcanizing ingredients may be included and thematerial vulcanized, satisfactory results are obtained Withoutvulcanization. After the final pressing step the material, if to be usedfor shoe bottoming, is

then cut into the desired blanks, and in this connection it may bepointed out that the characteristics of the material are such that itmay be channeled,- skived, stitched or otherwise treated in the samemanner as genuine leather and by the use of the same machinery. Whereflexibility is not a paramount requisite the pressure limits may'extendbeyond 2000 lbs. as for example in using the material for purposes suchas pump valves, cups, etc.

Instead of forming the wet sheet on a continuous type of paper machinesuch as the Fourdrinier or cylinder type it may be built up by the useof a wet or board machine, plying up on a suitable pick up or makingroll to the desired thickness, and then removing the sheet. If desired,an aqueous dispersion of rubber, such as natural or artificial rubberlatex, may be sprayed or otherwise applied between the layers as theyare plied up on the making roll and the'latex may be com pounded withglue or other. suitable ingredients for the purpose of increasing ordecreasing the adhesiveness, tensile strength, etc. of the dispersedrubber. If glue is used it may beset or not as desired by. the use offormaldehyde, tannic acid or other suitable agent. The use of glue inthis way improves the bond between the plies and also adds tothe waterresistance. The wet sheet as obtained from the cylinder machinemay thenbe subjected to the same pressing and drying operations as abovedescribed in connection with theproduct from the continuous sheetforming machine.

As an alternative to either of the above methods of forming thewetsheet, it may be produced by centrifugal deposition from the suspensionin the following manner:

, An ordinary centrifugal may be partitioned off into compartmentseither vertically or horizontally by pairs of walls of finelyperforated'metal or/ot-her suitable material spaced sufficiently to givethe. desired thickness of material and opening into a common cylindricalcompartment running vertically and parallel with the periphery of thebasket. 0n supplying the machine with the fiber-rubber. suspension, thematerial will be deposited in a sheet between the thickness,

partially built in the the case with a master walls.

sion of fiber and rubber, obtained as before described may be partiallydehydrated by allowing it to settle or by any other suitable means andthen the wet fibrous mass placed in asuitable mixing apparatus, such asaWerner-Pfieiderer mixer, and an additional amount of natural orartificial latex, such as a dispersion of rubber in water with orwithout the addition of glue or other suitable protective colloid, isadded to the batch in the mixer, and the mixing operation continueduntil the added rubber and other ingredients are uniformly distributedthroughout the mass. No coagulating step is used upon the portion of'therubber added to the batch in the mixing machine'and if the properprotective colloid is used, coagulation. does not take 'place until thematerial is dried. This mixing is continued until the batch is in aproper condition to be extruded through a suitable apparatus, which maybe an ordinary tuber or pug mill fitted with an. orifice capable ofgiving a shape to the material approximating that desired in thefinished product. The material may be cold pressed, dried with orwithout the intermediate pressing and then hot pressed as previouslydescribed. Alternatively, the product from the mixing machine may bepartially dried down to a moisture content of between 2030% and thenmade into sheet or ribbon form by any suitable means.

Another method of forming a sheet is to place the rubber fiber mixturebetween'two moving convergent wires or felt surfaces form of a verticalhopper so that as the bodyv of the rubberized fiber moves toward thebottom of the machine it is gradually compacted with the removal ofwater-until the sheet coming from the bottom orifice of the machine isof desired and with a sufiiciently low mbisture content so sheet frornanordinary Fourdrinier paper machine. This sheet is then pressed, driedand treated in every way as described above.

- Byour invention a leather substitute may be produced which is similarin appearance to leather of the sole leather or doubler types and in.whi'ch'the fibrous material is distributed continuously throughout thebody of thematerial, and is bonded by rubber either from natural latexor from an aque- .may be made therein without departing its spirit, andit is therefore not desired to that it can be handled as is ousdispersion of rubber (crude or reclaimed) uniformly distributed inminute particle form substantially invisible to the naked eye throughoutthe body of the material to form a'continuous fibroid flexible sheet,having the characteristic appearance of leather, especially afterabrasion, being dense and tough, and having a high flexing and tensiletest and a high resistance to water absorption and abrasion. Moreover,even after long exposure to moisture, it still.

retains its characteristic properties and is not softened, warped,,mushroomed and otherwise deteriorated-as is the case with leather. Itmay be manipulated in the same general-manner and by the same machineryas is used for leather. While it may con tain a relatively highpercentage of rubber, it has the general appearance and characteristicsof leather and has not the rubberlike feel and appearance of a, similarcom-' pound made by mixing fiber 6n a mill with plasticized rubber. Itsresistance to abrassion is also vastly superior to that of an ordinarymilled -rubber-fiber compound and the abrasion is very uniform.

While a specific disclosurehas been made of the invention, it is obviousthat changes from limit the invention more than is required by the priorart and as set forth in the appended claims.

Having thus described our invention, what we claim and desire to protectby lhetters Patent is:

1. The method of forming a fiber-rubber material which comprises formingan aqueous suspension of rubber and vegetable fiber,

depositing the rubber on the fiber, forming a relatively thick wet sheetmaterial therefrom, cold pressing the material without flowing orspreading it to compact it and remove moisture, drying the material tonot substantially over 15% moisture, and hot pressing at an increasedpressure.

2. The method of forming a fiber-rubber material which comprises formingan aqueous suspension of rubber and-vegetable fiber,

coagulating the rubber on the fiber, forming a relatively thick Wetsheet material thereflowing or spread-ing'itto compact it and removemoisture, drying the material to not substantially over 15% moisture,and hot pressing at over 800 lbs. pressure.

3. The method of forming a fiber-rubber material which'comprises formingan aqueous suspension of rubber and partly hydrolized vegetable fiber,coagulating the rubber on the fiber, forming a relatively thick wetsheet material therefrom, cold pressing the 7 from, cold pressing thematerial without material at not substantially over 1000 lbs.

pressure, drying to not substantially over .ous suspension of rubber to15% moisture, and hot pressing at over 800 lbs. pressure. i

, 4. The method of forming a fiber-rubber material which comprisesforming an aqueous suspension of rubber and partly hydrolyzed vegetablefiber, coagulating the rubber on the fiber, forming a relatively thickwet sheet material therefrom, cold pressing the material at notsubstantially over 1000 lbs. pressure, drying to not substantially over15% moisture, and hot pressing at 1400-2000 lbs. pressure.

5. The method of forming a fiber-rubber material which comprises formingan aqueous suspension of rubber and partly hydrolyzed vegetable fiber,coagulating the rubber on the fiber, forming a relatively thick wetsheet material therefrom, cold pressing the material without flowing orspreading it to compact it and remove moisture, material tosubstantially 10-15% moisture, and hot pressing at 1400-2000 lbs.pressure.

6. The method of forming a fiber-rubber material which comprises formingan aqueous suspension of rubber and partly hydrolyzed vegetable-fiber,coagulating the rubber on the fiber, forming a relatively thick Wetsheetmaterial therefrom, cold pressing the material at not substantially over1000 lbs. pressure, drying to substantially 10-15% mo sture, and hotpressing at not substantially over 2000 lbs. pressure.

-7. The method of forming a fiber-rubber material which comprises mixingan aqueou's suspension of partly hydrolyzed vegetable fiber and asuflicient amount of an aqueprovide 12-50% rubber, coagulating therubber on the fiber,

forming a relatively thick wet sheet material .therefrom, cold pressingthe material Without fiowing'or spreading it to compact it and removemoisture, drying the material to not substantially over 15%] moisture,and hot press ng at an increased pressure.

8. The method of forming a fiber-rubber -material which comprises mixingan aqueous suspension of partly hydrolyzed vegetable fiber and asuflicient amount of an aqueous suspension of rubber to provide 1250%rubber, coagulating the rubber on the fiber, forming a relatively thickwet sheet material therefrom, cold pressing the material at below 1000lbs. pressure, drying the material to not substantially over 15moisture, and hot pressing at over 800lbs; pressure.

, 9. The method of forming a fiber-rubber l I o 4 material whichcomprlses mlxing an aqueous suspension of partly hydrolyzed vegetablefiber and 'a sufiicient amount of an aqueous suspension of rubber toprovide 12-50%' rubber, coagulating the rubber of the fiber, forming arelatively thick wet sheet material therefrom, cold pressing thematerial without flowing or spreading it to compact it and removemoisture, drying to substandrying the tially 10-15% moisture, and hotpressing at over 1400 lbs. pressure.

10. The method of forming a fiber-rubber material which comprises mixingan aque- -ous suspension of partly hydrolyzed vegetable fiber with asufficient quantity of an aqueous suspension of rubber to provlde 12-50%rubber, coagulating the rubber on the Wet sheet material therefrom, coldpressing the material without flowing or spreading it to compact it andremove moisture, drying to not substantially over 1 5% moisture, and hotpressing at over 800lbs. pressure.

12. The method of forming a fiber-rubber material which comprisesmixing-an aqueous I suspension of vegetable fiber hydrolyzed to a partlygelatinous condition with a sufficient amount of an aqueous suspensionof rubber to rovide 12-50%- rubber, coagulating the ruber on the fiber,forming a relatively thick wet sheet material therefrom, cold pressingthe material at below 1000 lbs. pressure, dry- I ing to substantially10-15% moisture, and hot pressing at over 1400 lbs. pressure.

13. The method of forming shoe bottoming material which comprisesforming an aqueous suspension of rubber and fiber hydrolyzed to a partlygelatinous condition, coagulating the rubber on the fiber, forming arelatively thick wet-sheet therefrom, drying the sheet to notsubstantially over 30% moisture, cutting out shoe bottoming articlesfrom the sheet, cold mold pressing the articles at not to notsubstantially over 15% moisture, and hot pressing at'not substantiallyover 2000 lbs.

14. The method of forming shoe bottoming-material which comprises mixingan substantially over 1000 lbs. pressure, drying tively thick wet sheettherefrom, drying the sheet to not substantially over 30% moisture,

cutting out shoe bottoming'articles from the sheet, cold mold pressingatnot substantially,

over 1000 lbs. pressure, drying to substantialpressing at a ly 10-15%moisture, and hot pressure of 1400-2000 lbs.-

15. The method of manufacturing a fiberrubber material which comprisesforming a wet sheet of intimately intermingled. rubber particles andfibers,"pressing the Wet sheet at room temperature Without spreading it,drying the wet sheet to a moisture content of not over 15%, and pressingand completely drying the sheet at an elevated temperature.

16. The method of forming a fiber-rubber material which comprises mixingan aqueous suspension of partly hydrolyzed vegetable fiber and rubberlatex, coagulating the rubber on the fiber, mixing therewith a rubbervlatex in the presence of a protective colloid,

forming an article therefrom, partially dehydrating the material, coldpressing under moderate pressure, further dehydating, and hot pressingunder a higher pressure.

17 The method of manufacturing a fiberrubber material which comprisesforming a watery body of partly hydrolyzed vegetable fibers intimatelyassociated with ooagulated rubber particles, mixing therewith a watersuspension of rubber in the presence of a protective colloid, shaping anarticle therefrom, partially dehydrating, cold pressing, furtherdehydrating, and hot pressing under a higher pressure.

18. As a new article, a fiber-rubber material comprising a dense,compressed, relatively thick, flexible sheet of closely mattedrelatively long vegetable 'fibers, the individual fibers being spacedand strongly united by a relatively thin bond of gelatinized hydratedcellulose and the deposition product of an aqueous rubber disperslon.

Si 'ned at New York, county and State of New York, this 5th day ofAugust, 1927 REED P. ROSE. Signed atCleveland, county of Quyahoga andState of Ohio, this 8th day of August,

ALLEN F. OWEN.

